(Revised Abstract) DESCRIPTION (provided by applicant): The Radiochemistry/Bioconjugation Core (RBCC) resource will provide service in all aspects of ligands/bifunctional chelating agents (BFCAs) design and development, radiochemistry optimization in labeling with 99mTc and 111In, bioconjugation chemistry for linking BFCAs (or 99mTc/111ln labeled BFCs) to tumor avid target specific peptides. The RBCC Career Development facility will also provide a complete range of services toward the development and full characterization of metal complexes at macroscopic levels via the synthesis of Tc-99/Re complexes or In conjugates from appropriate BFCAs or peptide conjugates. The service activities of RBCC facility will encompass specific objectives of the P50 research and developmental projects and will work in close synergy with the Biotechnology Core Resource, Radiopharmacology Imaging Core Resource, Human Cancer Tumor Bank Core Resource and career development programs (Figure 1). The service, research and development efforts of RBCC as they relate to developing and optimizing bioconjugation protocols for linking target specific peptides to appropriate BFCAs will directly interface with the common objectives of the Biotechnology Core (BC) Resource and the Radiopharmacology Imaging Core (RIC) resource. Indeed, we plan to provide efficient synergy in the service activities of RBCC, BC and RIC core facilities so that the participating P50 investigators can reap maximum benefits from the respective cores. In addition to the technical staff working in the RBCC facility, we will recruit Post-Doctoral Fellows and undergraduate trainees from the career development program (within the P50 project directed by S. Lever) to undertake bioconjugation and radiochemistry projects that bear common rationale between the RBCC, BC and RIC core facilities. Development of functional and adaptable chelating agents and optimization of bioconjugation strategies, toward conjugation of BFCAs (or the 99rnTc (111ln) labeled BFCs), with biomolecules that express high affinity to antigens on carcinomas and metastases, would have a major impact on the rate and quality of development of highly sophisticated in vivo disease targeting radiopharmaceuticals. Therefore, a Radiolabeling and Bioconjugation Core Resource would provide the critically important service infrastructure needed for research, design and discovery of tumor specific radiolabeled diagnostic agents. A major goal of the Radiochemistry and Bioconjugation Chemistry Core Facility (RBCC) is to provide service in bifunctional chelating agent (BFCAs) design, develop radiolabeling protocols (using 99mTc or 111ln) and provide bioconjugation strategies for linking BFCAs or radiometal labeled BFCs to target specific biomolecules used within the P50 program. The RBCC resource will have state of the art infrastructure and expertise all aimed at providing radiolabeling and bioconjugation strategies to accomplish specific goals of the P-50 program toward conducting pilot imaging studies using the optimal 99rnTc or 111ln labeled peptide conjugates. The specific goals of the Radiochemistry and Bioconjugation Core Resource are: 1. Perform service toward the design and synthesis of optimal BFCAs for use in the production of high specific activity 99rnTc and 111ln labeled chelates. This goal will encompass synthesis of a wide spectrum of BFCAs, optimization of 99mTc and 111In labeling strategies and complete characterization of radiolabeled products. 2. Provide service in the development of viable strategies for the bioconjugation of target-specific peptides on to lead BFCAs or radiolabeled BFCs. This objective is specifically aimed at developing synthetic bioconjugation protocols via the .pre. or .post.-conjugation methodologies to maximize yields and achieve high purity of 99mTc or 111In labeled tumor-avid peptide conjugates. 3. Provide service in the synthesis and development of Tc/Re or In complexes at macroscopic levels with specific BFCAs or BFCA-peptide conjugates for macroscopic structure analysis and determination of binding affinities with receptor positive cancer cells.